1. Field of the Invention
The present invention relates to an electronic apparatus and, more particularly, to an electronic apparatus including a two-step switch.
2. Description of the Related Art
Recently, according to downsizing/weight saving of electronic apparatuses, much more cost reduction demands have been greatly required. For example, in an imaging apparatus, such as a digital camera, a shooting button, i.e., a release switch, is generally configured to provide two-step outputs, which are obtained by a difference of the amount of pushing in a pushing direction. Output of the first step, which is a small amount of pushing, is used for starting automatic focusing, and output of the second step, which is a large amount of pushing, is used for starting a photographing operation. Until now, to advance downsizing of an imaging apparatus, a small-sized two-step switch mounted on a circuit board has been often used as a release switch.
On the other hand, there is another type release switch not using a mounting type switch but using a flexible property of a substrate. In this type release switch, output of the first step can be obtained by causing opposite contact portions of the flexible substrate to contact each other. Then, output of the second step can be obtained by causing a dome-shaped plate spring, which is stuck on the flexible substrate by an adhesive sheet, to contact a contact point on the flexible substrate. With such a configuration, a release switch having an inexpensive configuration can be obtained. However, when an exterior portion of the digital camera is made of not conductive metal but resin, there is an issue that static electricity may invade a contact portion of the flexible substrate from the periphery of the release switch, so that electric parts on the flexible substrate may be broken.
To address this issue, there is a release switch using a coil spring for pushing up a key-top, which is an operation portion, as a countermeasure of invading of static electricity. In this case, Japanese Patent Application Laid-Open No. 2007-173094 discusses a configuration in which an earth (ground) pattern is formed at a position surrounding the contact portion on the substrate and the coil spring can contact the earth pattern. According to the discussion in Japanese Patent Application Laid-Open No. 2007-173094, since static electricity invading from the periphery of the key-top flows to the coil spring, invasion of the static electricity can be prevented.
However, as described above, a reduction of size of an electronic apparatus, such as an imaging apparatus, has been an indispensable requirement. In the configuration discussed in Japanese Patent Application Laid-Open No. 2007-173094, a great number of parts are required and a degree of height corresponding to the configuration of the two-step switch is necessary, so that such configuration is not suitable for the reduction of size.